Do doctors treat men and women too equally?

The FDA’s decision on Ambien renews push for gender-based medicine

By

JonnelleMarte

The Food and Drug Administration’s move last week to cut the recommended doses of sleeping pills like Ambien for women is drawing attention to an issue some researchers say is overlooked in the medical world: sex differences.

The shift was sparked by new research showing that sleep-inducing drugs linger in women’s bodies longer than in men’s, increasing the likelihood that they will be too drowsy in the morning to drive or stay alert. (The FDA halved the recommended dosage of all drugs containing zolpidem, the active ingredient in Ambien, to five milligrams for immediate-release versions of the pills and to 6.25 milligrams for extended-release versions.)

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It’s highly unusual for the FDA to set dosage guidelines based on patients’ sex, rather than age or weight, experts say. But as more research is conducted on the differences between male and female physiology, gender-based medicine could become far more common. “Men and women are different — their hearts, their lungs, their brains and their metabolisms are different,” says Phyllis Greenberger, president and chief executive officer of the Society for Women’s Health Research, a group pushing for more such research.

In recent years, health advocates have called for more studies focused on how various diseases and medications impact women differently than men. Such research was hampered by a previous policy enacted in 1977 that excluded women from participating in most clinical studies out of concerns that if the subjects were pregnant, such experimentation could harm a fetus. The FDA revised its policy in 1993 in response to a renewed push from advocates and scientific advances that made it easier to detect pregnancy. “If the research was done predominately on men, then how do we know that it’s relevant to women?” says Greenberger.

Female participation has increased since then, with most clinical trials using equal groups of both sexes, researchers say. Still, analyses of how a drug or treatment impacts men and women separately is often inconsistent, says Sabra Klein, an assistant professor of molecular microbiology and immunology at Johns Hopkins Bloomberg School of Public Health, who has been working to raise awareness of research showing that women develop stronger immune responses than men and may need smaller vaccination doses.

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Indeed, a 2010 report by the Institute of Medicine, sponsored by the Department of Health and Human Services found that while more women were participating in clinical trials, many researchers do not routinely analyze and report results separately for men and women, limiting the amount of information that could be used to develop effective treatments for women.

The zolpidem incident isn’t the first time women have had a more negative experience with a drug than men. A 2001 report by the Government Accountability Office, for instance, found that eight of the 10 drugs pulled off the market between 1997 and 2001 — including an appetite suppressant that lead to heart disease and a diabetes drug that increased the risk of liver failure — created greater health risks for women than for men. Some experts are concerned that women experiencing adverse side effects may alter their doses, or stop treatment early, on their own. “You don’t want women terminating treatment if the answer could just be that dosages should be different for men and women,” says Klein.

For its part, the FDA says it has been looking into the ways drugs can have different effects on men and women for some time. As a result, studies no longer examine just safety and efficacy, but pharmacokinetics, the process by which a drug is processed and eliminated by the body. Drug labels are also required to point out any differences seen in safety and effectiveness between genders, officials say. Still, it is unusual for doses to vary based on gender. Hypertension drug Norvasc, for instance, lists different side effects for men and women, but not a different recommended dose, says Sandy Walsh, a spokeswoman for the FDA.

To be sure, in many cases, one’s sex has little or no impact on the effect of a particular medication, says Klein. And even when there appears to be a discernable difference, it’s possible that other factors are at work. For instance, while some women may have greater blood levels of a drug when they are given the same dose as men, that often has more to do with size than gender, says Walsh.

Still, sex is likely to be taken into account more often. It may also become easier to note the differences in the ways men and women react to medications and diseases as doctors and hospitals increase their use of electronic health records, a shift that could make such data more readily available, says Klein.

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